Companions of Arterial Compliance in Male and Female Heart Failure Patients

Abstract

Arterial compliance (C) is defined as the ratio of stroke volume (SV) to pulse pressure (PP). Reflecting a major risk factor in terms of overall vascular stiffness, the estimation of C is clearly of clinical importance. As SV and PP each refer to a difference, their numerical values leave some uncertainty which can only be compensated by considering the Pythagorean mean. Therefore we explore the impact of these companion metrics, denoted as SVC and PPC, respectively.We retrospectively analyze the sex‐specific impact of SVC and PPC in heart failure (HF) patients, using central (aortic) pressure, combined with ventricular volume determinations by 2D angiocardiography. After obtaining informed consent, data were collected in 197 HF patients (130 men) who underwent cardiac catheterization at the Cardiovascular Center in Aalst (Belgium). SV is calculated as end‐diastolic volume (EDV) minus end‐systolic volume (ESV).Average indexed (i) SVi = 50.46 (±19.65) mL/m2 and average PP = 71.53 (± 27.09), resulting in average C = 0.80 (± 0.45) mL/mmHg.m2. However, PP and PPC are higher (P<0.0001) in women compared to men, yielding 84.8 ± 29.9 vs 64.7 ± 22.7 mmHg, and 167.8 ± 34.1 vs 150.0 ± 26.6 mmHg, respectively. SVi (P=0.45) and SViC (P=0.15) are not different for the sexes. Apart from sex‐related differences it is also important to consider the vast ranges occupied by the companions: 31.4 to 220.4 mL/m2 for SViC, and 79.9 to 282.3 mmHg for PPC. This divergence means that the isolated use of C only provides an incomplete presentation.In terms of hemodynamics the PPC can be interpreted as mean arterial pressure (MAP), as the two yield high correlations: R=0.948 for men and R=0.950 for women. Thus, PP and MAP emerge as complementary metrics. The SViC can be identified as a surrogate measure of preload, as this metric correlates with EDVi, yielding R=0.852 for men and R=0.952 for women. Therefore, plotting SVi versus its companion is similar to creating an ensemble‐based Starling curve.For women ESVi is smaller (P=0.003) than in men, implying that all derived metrics such as effective arterial elastance, ejection fraction, SViC and ventriculo‐arterial coupling are affected in a sex‐specific manner.We conclude that compliance data should be interpreted in a sex‐specific manner, and that the isolated use of C precludes full insight if the contributions of associated companions are neglected.Arterial compliance can be defined as the ratio of stroke volume index (SVi) to pulse pressure (PP). As SVi and PP are differences between paired measurements, it is required to consider their companion, derived from the Pythagorean mean. This figure illustrates the distribution of the companions in 197 heart failure patients.Figure 1